Driven by energy sustainability and environmental concerns, increasing endeavors have been made in developing and applying synthetic biology tools in cyanobacteria in recent years. One of the key elements to assure success of such efforts is to establish genetic transformation methodologies of high efficiency in cyanobacteria. Since its first demonstration in cyanobacterium Anacystis nidulans 602 in 1970, genetic transformation protocols for a variety of cyanobacterial species have been developed and optimized. However, despite the exciting achievement made in the past decades, the transformation efficiency in cyanobacteria is still typically lower than other model systems, such as E. coli and yeast.